As an iron core included in an electromagnetic relay, an iron core 5 manufactured by a method illustrated in FIGS. 14A through 14C is currently used, for example. In this method, an intermediate product 2 which is substantially I-shaped as viewed from the top is punched from a plate magnetic material 1 by press working. Then, magnetic poles 4 having a large width are formed by bending and raising upstanding portions 3 positioned at both ends of the intermediate product 2 to obtain the iron core 5 (see JP-A-6-196072).
In the punching process by press working, however, it is not easy to punch the intermediate product 2 by press working such that the width of the intermediate product 2 is smaller than the thickness of the plate material, and it is thus extremely difficult to obtain the iron core 5 having a smaller width than its height at a barrel 6. Therefore, when a predetermined amount of a coil 7 is wound around the barrel 6 of the iron core 5 so as to secure desired attractive force, the coil 7 protrudes in the horizontal direction as well as in the vertical direction as viewed in FIG. 14D. Accordingly, a thin electromagnet block 8, and thus a thin electromagnetic relay 9 are not manufactured.